Global Warming Continued
I have been
fairly critical of the report issued by the International Climate Change Taskforce, as commissioned by the Center For American Progress and two foreign groups.
Now, I'm not a scientist, so I can't get into the technical aspects of climate change. However, that is not what the role of a blogger is anyway. We're supposed to be the Cyber Sherpas, as coined by
Hugh Hewitt; guides to the top of the mountain of data. I can't be the expert, but I can point the way to his house.
Here's a
debate about global warming by two scientists. One is the famed science fiction writer, Jerry Pournelle, the other is Gavin Schmidt, a scientist with NASA. The debate is fairly long and occasionally technical, but not difficult to follow.
Pournelle raises some points that seem to me to be critical:
The models so far do not seem able to take the initial conditions of 1900 and get us to the year 2000 with any accuracy whatever. But they sure can take the conditions of 2004 and tell us about the year 2020!
This has always struck me as a critical flaw in the global warming models. To give a sports analogy, suppose I were to tell you that I'd constructed a model that projects that Alex Rodriguez will close out his career with 853 home runs. There are two methods of checking the model. First, we could wait for another 14 years or so and see where he ends up. And second, we could test the model against past players who have already finished their careers to see how well it predicted their future performance back when they were A-Rod's age.
Here's a simple home run projection model. Take the player's age and subtract 20. Divide the result into the number of home runs the player has already had. Multiply the result by 20 and that's how many homers the player will have at the end of his career. Working with A-Rod, he's 29 and he has 384 homers so far, so we would project him to 853 by the following formula: (384/(29-20))*20 = 853.
So now we look at some other famous ballplayers and see how well the model works. Hank Aaron had 342 at A-Rod's age; that projects out to 760. Aaron actually closed out his career with 755, so we would certainly say that the model worked with him. The method does not work as well with Babe Ruth, who only had 284 homers at that age, which would project out to 631, quite a bit short of Ruth's actual total of 714. Of course, it's not hard to see why; Ruth spent the early years of his career toiling as a pitcher and did not start accumulating homers until he was about 24.
Okay, the point is not to present my very simple projection system for home runs, but to highlight that if you want people to accept your projections, it's a very good idea to be able to show that they work well with past data. And as Pournelle notes, the global warming models do not project 2000's weather accurately based on past data.
Also, note this comment from Pournelle:
And tell me about your climate model that explains why things were warm around 800-1000 AD and got cold starting about 1300, until in 1776 the Hudson was frozen solid enough to bring cannon across. Show me a model that doesn't require me to let you pick arbitrary start and stop years to establish climate trends.
Kind of interesting, that, because as it happens, the report issued by the ICCT takes as its baseline the year 1750:
...[W]e propose a long-term objective of preventing the average global surface temperature from rising more than 2 degrees C (3.6 degrees F) above its pre-industrial level (taken as the level in 1750, when carbon dioxide (CO2) levels first began to rise appreciably as a result of human activities).
Got it? They pick as a baseline, an era when the planet was quite a bit colder (the Hudson frozen?) and say, "Let's not get too far away from that."
More on this topic later. Hat Tip to
Instapundit for the link to the Pournelle page.
